Post Spark Plug Change: Car will die occasionally when depressing clutch for a stop

I recently changed my plugs with stock replacement iridiums and everything seems peachy. I torqued them to the proper spec, coil packs seated properly, etc and the car starts and runs fine. There are no codes, misfires, or any lack of power (if anything it pulls harder). After an ECU reset however when coming to a stop and depressing the clutch pedal the car will literally drop rev's and die, no previous symptoms and it will start back up and drive away fine. Its happened a few times now after I had to pull the battery or reset via AP. The car is running an old protune from 2007 and has a list of mods. Is the car simply readjusting fuel trims or did I screw up my plug install? Any insight would be much appreciated.

All the vacuum lines plugged in? Any loose or cracked?

Same thing happened to me after changing the clutch (My battery was out of the car for awhile) The ECU just needs to "re-learn" how to idle. Give it a few start / stop cycles and you should be fine.

All the hoses and lines have good connections and are in great shape. Take some datalogs and maybe have someone take a look?

How long have you driven it since the reset? As mentioned, it does take a while to settle in.

PCV valve? Neutral Safety Switch?

 

I read that pcv valve sometimes causes rough idle and stalls the car.

On my 02 obs when I was coming to a stop and press the clutch pedal the car would shut down, it was the neutral safety swicth.

On my wife's 03 outback we were told it was the idle air control valve but we just cleaned the plugs and the valve and it's ok for now.

Are you sure you got the right plugs?

Id put money on ecu needing to re-learn idle and such, especially if plugs were right and there are no loose connections

Did it once to me when I switched plugs too. Also hit fuel cut once.

 

If it keeps doing it, you'll have to pull the plugs and check the gaps.

Are you sure you got the right plugs?

 

Pretty sure. I'm running the NGK-ILFR6B, exact ones I pulled out of the car.

 

How long have you driven it since the reset? As mentioned, it does take a while to settle in.

 

I've only been driving it briefly for the past few days. I'll have to report back once more time elapses. It just seems strange because before I changed the plugs if I reset the ECU I never had this problem. Why does the idle take a while to settle in? Shouldn't the reset put the vehicle back to the flashed map parameters where idle should have been fine during the original tune?

FYI. Out of curiosity, I went to NGK's home page and looked up your car. It listed OE Laser Iridium, SILFR6A, 7913, 0.030, as the OE replacement.

 

Don't know if there is a significant difference between yours and the 6A's listed by NGK. *shrugs*

Pretty sure. I'm running the NGK-ILFR6B, exact ones I pulled out of the car.

 

Those are not the OEM plugs

 

These are:

 

FYI. Out of curiosity, I went to NGK's home page and looked up your car. It listed OE Laser Iridium, SILFR6A, 7913, 0.030, as the OE replacement.

Looks like you are correct. I actually pulled out SILFR6A's. The manual reports the ILFR6B as the replacements but clearly the stock plugs are the 6A. The plugs seem nearly identical. I'll swap them out if the problem continues *sigh*

I believe you all were right, the car just had to "relearn" how to idle thanks for the help! I haven't had any problems for the last two days. Out of curiosity, would a stock vehicle have to relearn how to idle if it were reset or do the mods have a direct impact?

A stock vehicle would need to relearn for proper idle as well.